6.5 Specialty Slide Rules

While the majority of slide rules consisted of logarithmic scales for performing general calculations, many were designed for specific computations for very specific tasks. Just as a modern computer program might be used to perform a repeated calculation rather than typing in a series of similar computations again and again on an electronic calculator, special slide rules were developed for repeated calculations such as those found in the fields of electricity and electronics, chemistry, surveying, and so forth. Below are lists of slide rules that may be considered specialty rules in that they have scales specifically designed for use in a particular application or for a particular profession. Approximately 17% of the slide rules in the collection – 57 in total – are specialty rules.

The size Lx listed in these tables is the length in inches of the item’s greatest dimension, and not necessarily the length of a scale’s decade.


Gauging/Excise Carpenter/Engineer Aviation Chemical
Electro Electronics Engraving/Proportions Military
Spring Design Stadia (Surveying) Weight Calculations Other Specialties

6.5.1 Barrel Gauging and Excise Taxation Rules

Maker Model Year Type Lx Note
Gill Comparative Rule 1816-1824 L 9 Comparative Rule, part of a Sikes Hydrometer set made by Thomas Gill, London (in business 1806-1824)
Gill Proof Rule 1816-1824 L 9 Proof Rule, part of a Sikes Hydrometer set made by Thomas Gill, London (in business 1806-1824)
Dring and Fage Excise Officers Rule 1845-1849 L 10 double slide; Tooley St. (19 & 20) London address; boxwood; brass pins at gauge marks; no Inland Revenue mark
noID Comparative Rule
1880 L 9 nice boxwood Comparative Rule for alcohol taxation, likely from a Sikes’ hydrometer set; one side does comparative values; other side does reducing calc
Dring and Fage Inland Revenue Rule 1883-1902 L 24 Marked with address 145 Strand, London; used for alcohol excise tax purposes; 24 inch total length

6.5.2 Carpenter and Engineer Rules

Maker Model Year Type Lx Note
Belcher Bros.  Engineer’s Rule 1831-1843 L 12 Belcher made earliest American-made Gunter, Carpenter, and Engineer rules, starting in 1821; label BELCHER/BROTHERS/MAKERS/NEW YORK is from 1831-1843
Davies Routledge Engineer
1840 L 12 Maker is T. Davies, Gravel Lane, Southwark; references to pre-imperial units
Stanley No. 15
1858 L 12 Early American 2-foot 2-fold carpenter’s rule; Stanley Rule Level Co. No. 15; New Britain, Conn. (no USA); Warranted Boxwood; brass slide
Scofield Engineer’s Slide Rule 1901 L 24 rare; early edition of slide rule patented by Thacher, 1/2-assigned to Edson Mason Scofield (1867-1939); paper scales on wood, varnished; 1901 patent, no 1902 patent; sold by Dietzgen from about 1901-1931, perhaps also by Scofield

6.5.3 Aviation Slide Rules

Maker Model Year Type Lx Note
Felsenthal AN 5837-1 1943 C 8.0 Altitude Correction Computer; B/W main spiral scale, with fluorescent markings; WWII
Felsenthal D-4 1944 C 4.0 Time Distance Computer Type D-4; WWII device; Property of U.S. Army Air Forces; fluorescent numbers on black background
Felsenthal FAA-95 1950-1955 C 8.0 MB-1 Computer, Air Navigation, True Airspeed and Altitude; true altitude correction spiral on back
Blundell Rules Limited Pilot Balloon Slide Rule Mark IV-A 1957-1964 L 24.5 Used by the U.K. military/meteorologists to compute wind speed at various altitudes using data from sightings of “weather” balloons from ground-based telescopes; special thanks to Laurie,Peter(!),Stephen,Olivia,Arden for getting this to me from Australia
Felsenthal Dial-A-Con 1968 C 7.0 Flight computer, Type E6B, with instruction manual (by A. Fuchs), and vinyl case

6.5.4 Chemical Slide Rules

Maker Model Year Type Lx Note
Nestler 33 Chemiker 1928-1933 L 10 Early Chemical Rule, Albert Nestler A.G. LAHRi/B D.R. Patent Germany; Pickworth Data Slip on back; wide 1-line cursor
Hemmi 257 1956 L 10 Chemical Engineering; owner Frank Banks of CA

6.5.5 Electro Slide Rules

Maker Model Year Type Lx Note
Faber-Castell 378 1913-1914 L 10 Electro rule; nice condition; Made in Germany; no date marks; DRP No. 206428; Dynamo / Eff and V scales in well; W gauge on C; serif M on A/B
K&E 4133 1913-1914 L 8 Roylance Electrical Slide Rule, mahogany, early release; prod mark 255; used and in poor condition; missing original 3-hairline cursor
Nestler 37 1922-24 L 10 rule in very nice condition; stamp 391 on end; steel leaf springs
Faber-Castell 379 1923 L 5 Electro rule; nice condition; pearwood; Made in Bavaria and date marks 3 and 12 on back; V and Eff scales in well; W gauge on C
Hemmi 80/3
1935 L 10 Electro; tables on back and text on box in French
K&E N4133 1944 L 8 Roylance Electrical Slide Rule, mahogany; 3-hairline cursor; scale set #3; original case and box

6.5.6 Electronics Slide Rules

Maker Model Year Type Lx Note
K&E 4139 1946 L 10 Cooke Radio Slide Rule; Case: Polyphase Duplex DeciTrig 4071-3S
Pickett N-515-T 1958-62 L 10 Electronics model; leather case, strap – great condition; Cleveland Institute of Electronics
Pickett N-515-T 1958-62 L 10 Electronic; basically new-in-box; leather case, strap – great condition; Cleveland Institute of Electronics
Concise 380
1959-1966 C 4 Radio Computer, with instruction sheet; Concise Co., Ltd. 

6.5.7 Engraving/Proportions Slide Rules

Maker Model Year Type Lx Note
P.A.S. Co.  Engraving Rule
1928 L 7 Engraving Proportion Scale; sold by Art Brown & Bro. Inc. NewYork; similar to Hyde Optical Slide Rule at ISRM
Lawrence 10-C 1935-1938 L 5 Lawrence Engravers / Photographers Proportion Calculator; Wabash, IN
noID Engraving Rule
1940 L 20 18 inch proportions rule, perhaps used in printing, engraving; maker? American Blueprint? (similar construction to U.S. Military Rule); A/B scales range from 1 to 30, 12 inches from 1 to 10
Lawrence 10-N
1946 L 10 Lawrence Printer’s Proportion Rule; Peru, IN
Graphic Calculator Percentage Calculator 1962 C 6 Circular Proportions Rule, made in nearby Barrington, IL
C-Thru PS-79
1970 C 6 Proportional Scale, from the estate of Johnny Craig, noted comic book artist

6.5.8 Military Slide Rules

Maker Model Year Type Lx Note
Richardson Model of 1917 1917-1918 L 18 WW I military slide rule for ranging calculations; mahogany on brass; described in Richardson’s Slide Rule Simplified, 6th Ed.; made for J.H. Weil & Co., Phila.
Sillcocks-Miller M1 Slide Rule No. 547 1942 C 12 Military ballistic slide rule; angles in mils (800 mils = 45 deg); designed by Robert Crichlow
Hemmi Byoutou 1944 L 11 Military artillery or navigation rule? various scales using sines/tangents in degrees and in mils
American Blueprint Military 1948-1957 L 12 US Military slide rule, for field artillery problems
Blundell Rules Limited Radiac No. 1 1952-1956 C 5 radiation exposure calculator; log log scales; reversible land/sea discs; instructions on back
Pickett 14 1958-1962 L 10 U.S. military rule; well-worn leather case
USSR Military Slide Rule RL 1970 C 7 Translations: Slide Rule RL, GIVING AN ASSESSMENT OF THE RADIATION ENVIRONMENTS DURING GROUND EXPLOSIONS, For Official Use, Ex. No. D10342; Instruction booklet in Russian: Order of the Red Banner of Labor, Military Publishing House, Defense Ministries CCCP, Moscow – 1970; green plastic carrying case; gift from Brian Eddy (thanks!)

6.5.9 Spring Design Slide Rules

Maker Model Year Type Lx Note
Sandish Spring Calculator
1940 L 20 apparent home-made dual-slide spring calculation slide rule; traced by F. Sandish; original owner M.L. Rowe
Baetzmann Spring Calculator 1941 L 17 Spring Load Calculations slide rule; large format 17 in x 2.5 in x 0.75 in; two slides on front, one on back; owner (maker?) R. K. Baetzmann, 1941
J.B. Carroll Associated Spring M110 1952 L 10 early version, made for Associated Spring; no cursor
Pickett 1025 1952-1956 L 10 Early model 1025; owner Arthur E Huse, engraved on rule; signed home-made box; engineer for Bosch Arma with many patents related to fuel injection
Acu-Rule Connecticut Spring 1955 L 10 Spring design calculations rule,version 3, made for Connecticut Spring Corp. 

6.5.10 Stadia (Surveying) Slide Rules

Maker Model Year Type Lx Note
Kolesch 2713 Stadia 1905-1911 L 10 stadia rule, 360deg, D.R.Patent No. 173660, likely made by Nestler; advertised in 1907 How to use Slide Rules; suede leather case; owner Everett Gowty, Perry, OK
K&E 4100 1913-1915 L 10 Stadia rule, early model, for use in surveying; instructions on back; all-glass cursor; prod marks 268 on end
K&E N4100 1938 L 10 Stadia rule, for use in surveying; instructions on back; metal rimmed cursor
Aristo 958 1970 L 10 Geodat 400g stadia rule; instructions (German), clip-on supports; 5-hairline cursor; box and 1364 insert

6.5.11 Weight Calculation Slide Rules

Maker Model Year Type Lx Note
Novotni Weight Calculator
1935 L 15 Novotni, but not marked as such; 13 inch o/a length; By-Products Steel Corporation; Commercial Trust Building, Philadelphia, Pa.
Pickett N-550-T 1962 L 10 Warren-Knight Weight Rule 1373-ET; Label Style 3 with copyright 1962

6.5.12 Other Specialty Slide Rules

Maker Model Year Type Lx Note
E.S.A. London Harrow Mark Reducer 1898-1925 L 36 Educational Supply Association, incorp. 1898; rule was designed in 1875 by W.D. Bushell for the Harrow School, England, to reduce and calculate examination scores; 2 decades on stock, 3 decades on slide, 36 inch total length
Acu-Rule Arel G-W Photo 1946 L 10 Goodchild-Whitney (G-W) Photo Slide Rule, with instruction book
Lawrence 10-D
1946 L 10 Lawrence Lumber Calculator; Peru, IN
Richardson GE Analizer
1951 L 18 General Electric Company Quantity Analizer; similar construction to Richardson/J.H.Weil Slide Rule of 1917, apparently re-purposed; slots apparently for cursor on edges; GE logo from c.1951
Pickett N1040-ES 1954 L 10 Fisher Control Valve Sizing Rule; made for Fisher Governor Co, Marshalltown, Iowa
Kahl Scientific Culbertson Slide Rule 1955 C 8 Temperature, Depth, Salinity calcs; Designed by Margaret Culbertson for the U.S. Navy Electronics Lab; full instructions
Faber-Castell 3/11 Statique 1960 L 15 Rare, for reinforced concrete calculations; Spanish version

Below is a histogram of Specialty Slide Rules in the Collection as distributed over the decades of the 19th and 20th Centuries: